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Commit 7b4df058 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
Browse files

Btrfs: add helper for em merge logic 



This is a prepare work for the following extent map selftest, which
runs tests against em merge logic.

Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 18e83ac7

fs/btrfs/ctree.h

+2 −0
Original line number Diff line number Diff line
@@ -3143,6 +3143,8 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode, 
						    int delay_iput);

void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work);



int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,

			     struct extent_map **em_in, u64 start, u64 len);

struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,

		struct page *page, size_t pg_offset, u64 start,

		u64 len, int create);

fs/btrfs/inode.c

+46 −34
Original line number Diff line number Diff line
@@ -6925,6 +6925,51 @@ static noinline int uncompress_inline(struct btrfs_path *path, 
	return ret;

}



int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,

			     struct extent_map **em_in, u64 start, u64 len)

{

	int ret;

	struct extent_map *em = *em_in;



	ret = add_extent_mapping(em_tree, em, 0);

	/* it is possible that someone inserted the extent into the tree

	 * while we had the lock dropped.  It is also possible that

	 * an overlapping map exists in the tree

	 */

	if (ret == -EEXIST) {

		struct extent_map *existing;



		ret = 0;



		existing = search_extent_mapping(em_tree, start, len);

		/*

		 * existing will always be non-NULL, since there must be

		 * extent causing the -EEXIST.

		 */

		if (start >= existing->start &&

		    start < extent_map_end(existing)) {

			free_extent_map(em);

			*em_in = existing;

			ret = 0;

		} else {

			/*

			 * The existing extent map is the one nearest to

			 * the [start, start + len) range which overlaps

			 */

			ret = merge_extent_mapping(em_tree, existing,

						   em, start);

			free_extent_map(existing);

			if (ret) {

				free_extent_map(em);

				*em_in = NULL;

			}

		}

	}



	ASSERT(ret == 0 || ret == -EEXIST);

	return ret;

}



/*

 * a bit scary, this does extent mapping from logical file offset to the disk.

 * the ugly parts come from merging extents from the disk with the in-ram
@@ -7138,40 +7183,7 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, 


	err = 0;

	write_lock(&em_tree->lock);

	ret = add_extent_mapping(em_tree, em, 0);

	/* it is possible that someone inserted the extent into the tree

	 * while we had the lock dropped.  It is also possible that

	 * an overlapping map exists in the tree

	 */

	if (ret == -EEXIST) {

		struct extent_map *existing;



		ret = 0;



		existing = search_extent_mapping(em_tree, start, len);

		/*

		 * existing will always be non-NULL, since there must be

		 * extent causing the -EEXIST.

		 */

		if (start >= existing->start &&

		    start < extent_map_end(existing)) {

			free_extent_map(em);

			em = existing;

			err = 0;

		} else {

			/*

			 * The existing extent map is the one nearest to

			 * the [start, start + len) range which overlaps

			 */

			err = merge_extent_mapping(em_tree, existing,

						   em, start);

			free_extent_map(existing);

			if (err) {

				free_extent_map(em);

				em = NULL;

			}

		}

	}

	err = btrfs_add_extent_mapping(em_tree, &em, start, len);

	write_unlock(&em_tree->lock);

out: